Пример:
Выбрать другой фон для примера:
HTML:
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<canvas id="spider"></canvas> |
CSS:
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#spider { width: 100%; height: 500px; background-color: #337AB7; background-image: url(background.jpg); background-size: cover; background-position: center; margin: 20px 0; } |
JS:
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window.requestAnimFrame = function () { return ( window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) { window.setTimeout(callback); } ); }; function init() { let canvas = document.getElementById("spider"), c = canvas.getContext("2d"), w = (canvas.width = spider.offsetWidth), h = (canvas.height = spider.offsetHeight ); c.fillStyle = "rgba(30,30,30,1)"; c.fillRect(0, 0, w, h); return { c: c, canvas: canvas }; } window.onload = function () { let c = init("canvas").c, canvas = init("canvas").canvas, w = (canvas.width = spider.offsetWidth), h = (canvas.height = spider.offsetHeight), mouse = { x: false, y: false }, last_mouse = {}; function dist(p1x, p1y, p2x, p2y) { return Math.sqrt(Math.pow(p2x - p1x, 2) + Math.pow(p2y - p1y, 2)); } class segment { constructor(parent, l, a, first) { this.first = first; if (first) { this.pos = { x: parent.x, y: parent.y }; } else { this.pos = { x: parent.nextPos.x, y: parent.nextPos.y }; } this.l = l; this.ang = a; this.nextPos = { x: this.pos.x + this.l * Math.cos(this.ang), y: this.pos.y + this.l * Math.sin(this.ang) }; } update(t) { this.ang = Math.atan2(t.y - this.pos.y, t.x - this.pos.x); this.pos.x = t.x + this.l * Math.cos(this.ang - Math.PI); this.pos.y = t.y + this.l * Math.sin(this.ang - Math.PI); this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang); this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang); } fallback(t) { this.pos.x = t.x; this.pos.y = t.y; this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang); this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang); } show() { c.lineTo(this.nextPos.x, this.nextPos.y); } } class tentacle { constructor(x, y, l, n, a) { this.x = x; this.y = y; this.l = l; this.n = n; this.t = {}; this.rand = Math.random(); this.segments = [new segment(this, this.l / this.n, 0, true)]; for (let i = 1; i < this.n; i++) { this.segments.push( new segment(this.segments[i - 1], this.l / this.n, 0, false) ); } } move(last_target, target) { this.angle = Math.atan2(target.y - this.y, target.x - this.x); this.dt = dist(last_target.x, last_target.y, target.x, target.y) + 5; this.t = { x: target.x - 0.8 * this.dt * Math.cos(this.angle), y: target.y - 0.8 * this.dt * Math.sin(this.angle) }; if (this.t.x) { this.segments[this.n - 1].update(this.t); } else { this.segments[this.n - 1].update(target); } for (let i = this.n - 2; i >= 0; i--) { this.segments[i].update(this.segments[i + 1].pos); } if ( dist(this.x, this.y, target.x, target.y) <= this.l + dist(last_target.x, last_target.y, target.x, target.y) ) { this.segments[0].fallback({ x: this.x, y: this.y }); for (let i = 1; i < this.n; i++) { this.segments[i].fallback(this.segments[i - 1].nextPos); } } } show(target) { if (dist(this.x, this.y, target.x, target.y) <= this.l) { c.globalCompositeOperation = "lighter"; c.beginPath(); c.lineTo(this.x, this.y); for (let i = 0; i < this.n; i++) { this.segments[i].show(); } c.strokeStyle = "hsl(" + (this.rand * 20 + 180) + ",100%," + (this.rand * 40 + 25) + "%)"; c.lineWidth = this.rand * 2; c.lineCap = "round"; c.lineJoin = "round"; c.stroke(); c.globalCompositeOperation = "source-over"; } } show2(target) { c.beginPath(); if (dist(this.x, this.y, target.x, target.y) <= this.l) { c.arc(this.x, this.y, 2 * this.rand + 1, 0, 2 * Math.PI); c.fillStyle = "white"; } else { c.arc(this.x, this.y, this.rand * 2, 0, 2 * Math.PI); c.fillStyle = "darkcyan"; } c.fill(); } } let maxl = 300, minl = 50, n = 30, numt = 500, tent = [], clicked = false, target = { x: 0, y: 0 }, last_target = {}, t = 0, q = 10; for (let i = 0; i < numt; i++) { tent.push( new tentacle( Math.random() * w, Math.random() * h, Math.random() * (maxl - minl) + minl, n, Math.random() * 2 * Math.PI ) ); } function draw() { if (mouse.x) { target.errx = mouse.x - target.x; target.erry = mouse.y - target.y; } else { target.errx = w / 2 + ((h / 2 - q) * Math.sqrt(2) * Math.cos(t)) / (Math.pow(Math.sin(t), 2) + 1) - target.x; target.erry = h / 2 + ((h / 2 - q) * Math.sqrt(2) * Math.cos(t) * Math.sin(t)) / (Math.pow(Math.sin(t), 2) + 1) - target.y; } target.x += target.errx / 10; target.y += target.erry / 10; t += 0.01; c.beginPath(); c.arc( target.x, target.y, dist(last_target.x, last_target.y, target.x, target.y) + 5, 0, 2 * Math.PI ); c.fillStyle = "hsl(210,100%,80%)"; c.fill(); for (i = 0; i < numt; i++) { tent[i].move(last_target, target); tent[i].show2(target); } for (i = 0; i < numt; i++) { tent[i].show(target); } last_target.x = target.x; last_target.y = target.y; } canvas.addEventListener( "mousemove", function (e) { last_mouse.x = mouse.x; last_mouse.y = mouse.y; mouse.x = e.pageX - this.offsetLeft; mouse.y = e.pageY - this.offsetTop; }, false ); canvas.addEventListener("mouseleave", function (e) { mouse.x = false; mouse.y = false; }); canvas.addEventListener( "mousedown", function (e) { clicked = true; }, false ); canvas.addEventListener( "mouseup", function (e) { clicked = false; }, false ); function loop() { window.requestAnimFrame(loop); c.clearRect(0, 0, w, h); draw(); } window.addEventListener("resize", function () { (w = canvas.width = spider.offsetWidth), (h = canvas.height = spider.offsetHeight); loop(); }); loop(); setInterval(loop, 1000 / 60); }; |
Цвет паука задается в HSL строкой:
c.strokeStyle = "hsl(" + (this.rand * 20 + 180) + ",100%," + (this.rand * 40 + 25) + "%)";
а толщина его лап:
c.lineWidth = this.rand * 2;
Найдено на codepen.io у пользователя Becod
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